In a number of applications for space-based radars, collapsed antennas and ground planes are loaded into a space craft; and after reaching a particular orbit, each collapsed antenna is deployed to an operating position. When this happens, it is often necessary to move a ground plane adjacent the antenna radiating elements. A problem has existed in accomplishing precise movement of a ground plane from a stored condition to an operative condition relative to the antenna, in a manner ensuring a continuous ground plane surface free from RF leaks.